Evaluation of Analgesic Activity of Newly Synthesized Phthalyl- tyrosyl-glycin Sodium

Abstract

Alteration in the backbone structure of the endogenously released opioid peptides Leu⁵/Met⁵ enkephalins may result in compounds having comparable profile of pharmacological activity but with different physicochemical properties and side effects. Phthalyl amino acid and phthalyl esters are among the derivatives that have been synthesized and evaluated for their antibacterial and antifungal activities.This study was conducted to evaluate the possible analgesic activity of phthalyl-tyrosyl-glycin sodium that has been recently synthesized by our team.The study was carried out on 24 albino mice using hot plate method. The animals were allocated in to three groups; the first group received saline and represent a control group; the second group received morphine HCl as a standard drug; and the third group received phthalyl-tyrosyl-glycin sodium. The onset with which the animal lift his forearm and the number of jumps per 25 seconds were recorded for each group.

   The results of this study showed that phthalyl-tyrosyl-glycin sodium resulted in significant improvement (P<0.05) in analgesia score as well as significant delay in the onset of induced hyperalgesia in comparison to saline-treated group, and in comparison to morphine HCl, no significant difference (P>0.05) was observed in analgesia score but with significant delay in induced hyperalgesia.The results obtained in this study provide experimental evidences for the effectiveness of the prepared compound as analgesic with comparable effect to that of morphine.

Key words: Phthalyl-tyrosyl-glycin sodium, phthalyl group, analgesia